Variable coupling transformer



p l 1942- G. MONTI GUARNIERI ET AL 2,280,001

VARIABLE COUPLING TRANSFORMER Filed Dec. 13, 1959 Patented Apr. .14, 1942 VARIABLE COUPLING TRANSFORMER Gaetano Monti Guarnieri and Giacomo Caletti, Milan, Italy, asslgnors to Fabbrica Italiana Magneti Marelli Societa Anonima, Milan, Italy, a corporation of Italy Application December 13, 1939, Serial No. 309,080 In Italy December 29, 1338 11 Claims.

This invention relates to variable coupling transformers of the kind used in radio receiving sets and has for its object a coupling transformer of the above defined class which includes two intercoupled windings arranged at the side of each other and in which the variation of the coupling rate is secured by an angular displacement of one of said windings about an axis perpendicular to the axes of both windings.

An embodiment of this invention is shown by way .of example on the annexed drawing and- Fig. 1 is an elevation of a transformer of this invention with a screening shield therefor in section;

Fig. 2 is a side view of the transformer with the screening shield and other parts removed;

Fig. 3 is an inverted plan view of Fig. 2 and Fig. 4 is a fragmentary transverse section of Fig. 1 on line 44.

The transformer of this invention includes a supporting structure consisting of two parallel plate frames I and 2 of insulating material, said frames being interconnected by means of spacers 3, 4 and tubular rivet 5; the whole of the transformer is enclosed within a metal shield 6 whose side walls are provided with inward ribs Ii providing grooves in which the longitudinal edges of the frames I and 2 are engaged.

The shield 6 is open at one of its ends for the location of the transformer therein; the end wall of the shield 6 opposite to said open end thereof has an orifice 42 enabling the control means of the adjustable winding of the transformer as hereinafter described, to extend therethrough. p

At one ofitheir ends, the frames I, 2 provide adjacent registering prongs I, 2' which lie in the plane of the respective frame and provide forks extending inwardly of said frame each from the respective frame end towards the other one, said forks cooperating with the mounting of a stationary winding I. For cooperation with said prongs I, 2, the stationary winding 1 is located on an insulating support sleeve 8 which has pairs of transverse slots 9 by means of which it may be engaged on, the prongs I, 2' of the registering forks, the winding proper I being positioned intermediate said forks of the plate frames I, 2. The winding 1 and its supporting sleeve 8 are fastened in position on the prongs I, 2' by means of a tapped or screwthreaded core III which fits axially within the sleeve 8 and is screwed in circular recesses I", 2 provided in the facing edges of the prongs of each fork, said edges being engaged as a nut by the worm of the core I0.

As shown diagrammatically by dotted lines 38, 39, the two'ends of the winding 1 are connected with terminals II, 3| fast on the insulating frames I, 2 and extending outwardly of the shield 6; said shield 6 has an orifice, not shown, in

spacer 3 on which the registering ends of the frames I and 2 are fast.

The frame 2 has a cut-off portion in register with the location of the adjustable winding I3 to provide for an unrestricted angular motion of said winding I3 and core I5 about the axis of the spindle 20 and in register with said cut-off portion the frames I and 2 are interconnected 'by means of a recessed U-bridge 22 fastened to the frames I and 2 by means of rivets 23. Due to the provision of the recessed bridge 22, the adjustable winding I3 is enabled to take a position in which its axis is nearly perpendicular to, the axis of the stationary winding 1,. that is, it.

may take a position in which the value'of the winding intercoupling is a minimum; the shield 6 has an orifice 36 in register with the position which the outer end of the core I5 has when the winding I3 is in said position of minimum intercoupling so that the end of the core I5 may be grasped from the outside by means of a suitable implement to effect its calibration.

The spindle 20 is actuated by means of a bell shaped pulley 24 having its hub 25 clamped on the end of the spindle 20 by means of a set screw 26; said spindle 20 extends through the spacer 3 and an extension 3 thereof and is held longitudinally in position by means of a split ring 21 engaged in a groove 20 of the spindle 20.

The pulley 24 which is driven in one direction by means of a cord (not shown) attached thereto and wound thereon, is restored in the opposite direction by means of a return spring 28 located within it and embracing the extension 3' of the spacer 3; one end 28' of the spring 28 engages the pulley 24 while the opposite end 28" thereof engages the spacer 3.

The pulley 24 is further provided with a stop finger 29 travelling in a quadrant recess 30 of the spacer extension 3: said finger 29 may be properly set with respect to said recess 30 by setting the pulley 24, 25 in a proper angular position on the spindle 20.

One of the ends of the winding I3 is connected with leads 40, 2I, the ead 2I extending to the outside of the shield 6 through an orifice 34 thereof; the opposite end of the winding I3 is connected by means of leads 4| and 31, with a terminal I2 fast on the end of the insulating frames I, 2 where the terminals II and 3| are located.

The connections 31, 38, 39, 40, H of the windings i and I3 shown diagrammatically by dotted lines, may be soldered to conductive stubs 32 fast by means of tubular rivets 33 on the structure embodying the insulating frames l and 2; the stubs 32 provide the terminals ll, l2 and 3! at one one of said structure and said connection may extend through the tubular rivets 33 which secure the stubs 32 in position, as shown in respect of connection 31.

The opposed ends of the structure I, 2 have a similar configuration and accordingly the transformer may be reversed with respect to the illustrated position; when the transformer is arranged on the support plate 35 therefor with the adjustable winding l3 adjacent to said plate 35 'the control pulley 24, 25 extends beyond an oriflce 35 of said plate 35; the connections may in any case be provided through orifices of the base plate 35 and accordingly without requiring the provision of orifices in the walls of the shield 6, being then sufficient to remove the terminals ii, i2, 39 on the frame end adjacent to the stationary winding i' and locate said terminals on the frame end adjacent'to the pulley 24, 25, the connections being subsequently made by means of suitable leads.

Further in the above outlined arrangement it is not necessary to provide an orifice through the shield ii for the passage of the spindle 2t and the spacer extension 3 therethrough.

The described coupling transformer is simple and sturdy and it makes all connections and adjustments easy.

What we claim as our invention and desire to secure by United States Letters Patent is:

i. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive apertured plates of insulating material, spacers intermediate said plates at the ends thereof, means interconnecting said plates and l spacers in a frame structure, prongs in said plates adjacent one end thereof and extending inwardly of said frame structure towards the other end of said plates, a stationary transformer winding engaged in said prongs, a spindle rotatable in said structure and pivotally mounted in the one of said spacers located atsaid other end of said plates, isaid spindle extending on a line transverse to the axis of said stationary winding, an adjustable transformer winding mounted on said spindle to move therewith with its axis lying in a plane parallel with the axis of said stationary winding, said adjustable winding being adjacent to said stationary winding for variable coupling therewith, and means for actuating said spindle.

2. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive plate frames of insulating material, spacers intermediate said frames at the ends thereof, means interconnecting said frames and spacers in a structure, a stationary transformer winding engaged in said structure at one end of said frames, a spindle rotatable in said structure and pivotally mounted in the one of said frame spacers located at the other end of said frames,

said spindle extending on a line transverse to the axis of said stationary winding, 2. block fast on the end of said spindle within said structure, prongs fast on said spindle block and extending -towards said one end of said frames, an adjustadjacent to said stationary winding for variable coupling therewith and means for actuating said spindle.

3. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive plate frames of insulating material, spacers intermediate said frames at the ends thereof, means interconnecting said frames and spacers in a structure, prongs in said frames adjacent one end thereof and providing forks extending inwardly of said structure towards the other end of said frames said prongs of each fork having opposite depressions, a sleeve having transverse slots engaged on said forlr by said fork prongs entering said sleeve slots, a stationary transformer winding on the portion of said sleeve between said forks of said plate frames, a tapped winding core extending through said sleeve and screwed in the edges of said prong depressions, a spindle rotatable in said structure and pivotal- 1y mounted in the one of said frame spacers located at said other end of said frames, said spindle extending on a line transverse to the axis of said stationary winding, a block fast on the end of said spindle within said structure, prongs fast on said spindle block and extending towards said one end of said frames, an adjustable transformer winding mounted on said prongs to move with said spindle with its axis lying in a plane parallel with the axis of said stationary winding, said adjustable winding being adjacent to said stationary winding for variable coupling therewith and means for actuating said spindle.

4. A variabie coupling transformer for radio sets comprising two parallel and spaced coextensive plate frames of insulating material, spacers intermediate said. frames at the ends thereof, means interconnecting said frames and spacers in a structure, prongs in said frames adjacent one end thereof and extending inwardly of said structure towards the other end of said frames, a stationary transformer winding engaged in said frame prongs, a spindle rotatable in said structure and pivotally mounted in the one of said frame spacers located at said other end of said frames, said spindle extending on a line transverse to the axis of said stationary winding, a block. fast on the end of said spindle Within said structure, prongs fast on said spindle block and providing spindle forks extending inwardly of said structure towards said one end of said frames, said prongs of each spindle fork having opposite depressions, a sleeve having transverse slots engaged in said spindle forks by said spindle forlr prongs entering said spindle sleeve slots, an adjustable transformer winding on the portion of said spindle sleeve between said spindle forks, a tapped winding core extending through said spindle sleeve and screwed in the edges of said spindle prong depressions and means for actuating said spindle.

5. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive plate frames of insulating material, spacers intermediate said frames at the ends thereof, means interconnecting said frames and spacers in a structure, prongs in said frames adjacent one end thereof and providing forks extending inwardly of said structure towards the other end of said frames, said prongs of each fork hav' ing opposite depressions, a sleeve having transverse slots engaged on said forks by said fork prongs entering said sleeve slots, a stationary transformer winding on the portion of said sleeve between said forks of said plate frames, a tapped winding core extending through said sleeve and screwed in the edges of said prong depressions, a spindle rotatable in said structure and pivotally mounted in the one of said frame spacers located at said other end of said frames, said spindle extending on a line transverse to the axis of said stationary winding, a block fast on the end of said spindle within said structure, prongs fast on said spindle block and providing spindle forks extending inwardly of said structure towards said one end of said frames, said prongs of each spindle fork having opposite depressions, a sleeve having transverse slots engaged in said spindle forks by said spindle fork prongs entering said spindle sleeve slots, an adjustable transformer winding on the portion of said spindle sleeve between said spindle forks. a tapped winding core extending through saidspindle sleeve and screwed in the edges of-said spindle prong depressions and means for actuating said spindle.

' 6. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive apertured plates, spacers intermediates said and adjustable winding being adjacent to said stationary core and winding for variable coupling therewith, means foractuatlng said spindle and a screening shield encircling said structure and having grooves for engagement by the edges of said plates.

7. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive plate frames,- spacers intermediate said frames, means interconnecting said frames and spacers in a structure, a stationary winding core engaged in said structure, a stationary transformer winding on said core and in said structure, a spindle rotatable in said structure and extending on a line transverse to the axis of said stationary winding, a winding core mounted on said spindle to move therewith with its axis lying in a plane parallel with the axis of said stationary core and winding, an adjustable winding on said spindle core, said spindle core and .said structure and having orifices in register with said cores.

8. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive plate frames, spacers intermediate said frames, means interconnecting said frames and spacers in a structure, a stationary transformer winding engaged in said structure, a spindle rotatable in-said structure and extending on a line transverse to the axis of said stationary winding, an adjustable transformer winding mounted on said spindle to move therewith with its axis lying in a plane parallel with the axis of said stationary winding, said adjustable winding being adjacent to said stationary winding for variable coupling therewith, a hollow pulley fast on the end of said spindle extending outwardly from said structure and a return coil spring having its ends engaged with said pulley and said structure respectively.

9. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive' plate frames, spacers intermediate said frames, means interconnecting said, frames and spacers in a structure, a stationary transformer winding engaged in said structure, a spindle rotatable in said structure and extending on a line transverse to the axis of said stationary winding, an adjustable transformer winding mounted on said spindle to move therewith with its axis lying in a plane parallel with the axis of said stationary winding, said adjustable winding being adjacent to said stationary winding for variable coupling therewith, a hollow pulley fast on the end of said spindle extending from said structure, a finger on said pulley extending toward said structure, an extension in said structure embracing said spindle and confronting with said pulley, said structure having a quadrant shaped recess entered by said finger for a restricted rotation of said pulley and spindle with respect to said structure, and a return coil spring having its ends engaged with said pulley and said structure respectively.

10. A variable coupling transformer for radio sets comprising two parallel and spaced coextensive apertured plates of insulating material, spacers intermediate said plates at the ends thereof, means interconnecting said plates and spacers in a frame structure, a stationary transformer winding engaged in said parallel plates near one end of said structure, a spindle rotatable in said structure and pivotally mounted in the one of said spacers located at the other end of said structure. said spindle extending on a line transverse to the axis of said stationary winding, an adjustable transformer winding mounted on said spindle to move therewith with its axis lying in a plane parallel with the axis or said stationary winding, said adjustable winding being adjacent to sa d stationary winding for variable coupling therewith, and means for actuating said spindle,

11. A variablecoupling transformer for radio sets comprising two parallel and spaced'coextensive apertured plates, spacers intermediate said plates at the ends thereof, means interconnecting said plates and spacers in a frame structure, a stationary transformer winding engaged in said parallel plates near one end of said structure, a spindle rotatable in said structure and pivotally mounted in the one of said spacers located at the other end of said structure, said spindle extending on a line transverse to the axis of said stationary winding, an amustable transformer winding mounted on said spindle to move therewith with its axis lying in a plane parallel with the axis of said stationary winding, said adjustable winding being adjacent to said stationary winding for variable coupllng therewith, and means for actuating said spindle.

GAETANG MONTI GUARNIERI. GIACOMO CALE'I'I'I. 

